1. Field of the Invention
The present invention pertains to a method and system for mixing a soluble polymeric drag reducing additive with a relatively high pressure liquid flowing through a transmission pipeline, or the like.
2. Background
Certain types of high molecular weight linear chain polymer substances have been determined to be effective in reducing the friction pressure losses incurred in pumping relatively viscous fluids, such as crude oil, through transmission pipelines. The injection of relatively small quantities of these drag reducing additives into high volume crude oil pipelines, such as the Trans-Alaska Pipeline System, can result in significant savings in pumping costs and fluid transmission time. One commercially successful type of drag reducing additive is manufactured and sold under the trademark FLO.RTM. by Chemlink Petroleum, Inc., a subsidiary of the assignee of the present invention. However, certain problems are associated with pumping drag reducing additives and the injection of these additives into a pipeline to provide a competent drag reduction effect.
One problem associated with injecting polymer type drag reducing additives pertains to the lack of lubricity of the drag reducing additive itself. Accordingly, the use of high pressure metering pumps, such as Gear or lobe type pumps, for raising the pressure of the drag reducing additive for injection directly into the transmission pipeline results in a relatively short life of the injection or metering pump.
Another problem associated with the injection of the aforementioned type of drag reducing additive pertains to the degradation of the additive when subjected to sustained high velocity flow and the resultant shear forces acting on the additive material. In this regard, the injection of the material directly into the main fluid transmission line through jet nozzles and the like tends to degrade the drag reducing additive at the point of injection with almost instant loss of operating effectiveness.
Still further considerations in injecting polymer and other viscous type drag reducing additives pertains to the apparent ineffectiveness of the additive when it is not injected or mixed with the main fluid flow at a point near the inner wall surface of the fluid transmission pipeline, itself. However, the present invention provides a method and system for overcoming certain problems associated with the use of polymer type and certain other type relatively viscous fluid transmission pipeline additives.